This module caches authentication and authorization results based
on the configuration of mod_ldap. Changes
made to the backing LDAP server will not be immediately reflected on the
HTTP Server, including but not limited to user lockouts/revocations,
password changes, or changes to group memberships. Consult the directives
in mod_ldap for details of the cache tunables.

There are two phases in granting access to a user. The first
phase is authentication, in which the mod_authnz_ldap
authentication provider verifies that the user's credentials are valid.
This is also called the search/bind phase. The second phase is
authorization, in which mod_authnz_ldap determines
if the authenticated user is allowed access to the resource in
question. This is also known as the compare
phase.

mod_authnz_ldap registers both an authn_ldap authentication
provider and an authz_ldap authorization handler. The authn_ldap
authentication provider can be enabled through the
AuthBasicProvider directive
using the ldap value. The authz_ldap handler extends the
Require directive's authorization types
by adding ldap-user, ldap-dn and ldap-group
values.

During the authentication phase, mod_authnz_ldap
searches for an entry in the directory that matches the username
that the HTTP client passes. If a single unique match is found,
then mod_authnz_ldap attempts to bind to the
directory server using the DN of the entry plus the password
provided by the HTTP client. Because it does a search, then a
bind, it is often referred to as the search/bind phase. Here are
the steps taken during the search/bind phase.

Generate a search filter by combining the attribute and
filter provided in the AuthLDAPURL directive with
the username passed by the HTTP client.

Search the directory using the generated filter. If the
search does not return exactly one entry, deny or decline
access.

Fetch the distinguished name of the entry retrieved from
the search and attempt to bind to the LDAP server using that
DN and the password passed by the HTTP client. If the bind is
unsuccessful, deny or decline access.

During the authorization phase, mod_authnz_ldap
attempts to determine if the user is authorized to access the
resource. Many of these checks require
mod_authnz_ldap to do a compare operation on the
LDAP server. This is why this phase is often referred to as the
compare phase. mod_authnz_ldap accepts the
following Require
directives to determine if the credentials are acceptable:

Grant access if there is a Require ldap-user directive, and the
username in the directive matches the username passed by the
client.

Grant access if there is a Require
ldap-dn directive, and the DN in the directive matches
the DN fetched from the LDAP directory.

Grant access if there is a Require ldap-group directive, and
the DN fetched from the LDAP directory (or the username
passed by the client) occurs in the LDAP group or, potentially, in
one of its sub-groups.

Grant access if there is a Require ldap-attribute
directive, and the attribute fetched from the LDAP directory
matches the given value.

Grant access if there is a Require ldap-filter
directive, and the search filter successfully finds a single user
object that matches the dn of the authenticated user.

otherwise, deny or decline access

Other Require values may also
be used which may require loading additional authorization modules.

Specifies the LDAP objectClass values used to identify if queried directory
objects really are group objects (as opposed to user objects) during the
Require ldap-group directive's sub-group processing.

Apache's Require
directives are used during the authorization phase to ensure that
a user is allowed to access a resource. mod_authnz_ldap extends the
authorization types with ldap-user, ldap-dn,
ldap-group, ldap-attribute and
ldap-filter. Other authorization types may also be
used but may require that additional authorization modules be loaded.

Since v2.4.8, expressions are supported
within the LDAP require directives.

The Require ldap-user directive specifies what
usernames can access the resource. Once
mod_authnz_ldap has retrieved a unique DN from the
directory, it does an LDAP compare operation using the username
specified in the Require ldap-user to see if that username
is part of the just-fetched LDAP entry. Multiple users can be
granted access by putting multiple usernames on the line,
separated with spaces. If a username has a space in it, then it
must be surrounded with double quotes. Multiple users can also be
granted access by using multiple Require ldap-user
directives, with one user per line. For example, with a AuthLDAPURL of
ldap://ldap/o=Example?cn (i.e., cn is
used for searches), the following Require directives could be used
to restrict access:

Because of the way that mod_authnz_ldap handles this
directive, Barbara Jenson could sign on as Barbara
Jenson, Babs Jenson or any other cn that
she has in her LDAP entry. Only the single Require
ldap-user line is needed to support all values of the attribute
in the user's entry.

If the uid attribute was used instead of the
cn attribute in the URL above, the above three lines
could be condensed to

This directive specifies an LDAP group whose members are
allowed access. It takes the distinguished name of the LDAP
group. Note: Do not surround the group name with quotes.
For example, assume that the following entry existed in
the LDAP directory:

Members can also be found within sub-groups of a specified LDAP group
if AuthLDAPMaxSubGroupDepth
is set to a value greater than 0. For example, assume the following entries
exist in the LDAP directory:

The following directives would allow access for Bob Ellis, Tom Jackson,
Barbara Jenson, Fred User, Allan Jefferson, and Paul Tilley but would not
allow access for Jim Swenson, or Elliot Rhodes (since they are at a
sub-group depth of 2):

The Require ldap-dn directive allows the administrator
to grant access based on distinguished names. It specifies a DN
that must match for access to be granted. If the distinguished
name that was retrieved from the directory server matches the
distinguished name in the Require ldap-dn, then
authorization is granted. Note: do not surround the distinguished
name with quotes.

The Require ldap-attribute directive allows the
administrator to grant access based on attributes of the authenticated
user in the LDAP directory. If the attribute in the directory
matches the value given in the configuration, access is granted.

The following directive would grant access to anyone with
the attribute employeeType = active

Require ldap-attribute "employeeType=active"

Multiple attribute/value pairs can be specified on the same line
separated by spaces or they can be specified in multiple
Require ldap-attribute directives. The effect of listing
multiple attribute/values pairs is an OR operation. Access will be
granted if any of the listed attribute values match the value of the
corresponding attribute in the user object. If the value of the
attribute contains a space, only the value must be within double quotes.

The following directive would grant access to anyone with
the city attribute equal to "San Jose" or status equal to "Active"

The Require ldap-filter directive allows the
administrator to grant access based on a complex LDAP search filter.
If the dn returned by the filter search matches the authenticated user
dn, access is granted.

The following directive would grant access to anyone having a cell phone
and is in the marketing department

Require ldap-filter "&(cell=*)(department=marketing)"

The difference between the Require ldap-filter directive and the
Require ldap-attribute directive is that ldap-filter
performs a search operation on the LDAP directory using the specified search
filter rather than a simple attribute comparison. If a simple attribute
comparison is all that is required, the comparison operation performed by
ldap-attribute will be faster than the search operation
used by ldap-filter especially within a large directory.

The next example is similar to the previous one, but it
uses the common name instead of the UID. Note that this
could be problematical if multiple people in the directory
share the same cn, because a search on cnmust return exactly one entry. That's why
this approach is not recommended: it's a better idea to
choose an attribute that is guaranteed unique in your
directory, such as uid.

The next example assumes that everyone at Example who
carries an alphanumeric pager will have an LDAP attribute
of qpagePagerID. The example will grant access
only to people (authenticated via their UID) who have
alphanumeric pagers:

The next example demonstrates the power of using filters
to accomplish complicated administrative requirements.
Without filters, it would have been necessary to create a
new LDAP group and ensure that the group's members remain
synchronized with the pager users. This becomes trivial
with filters. The goal is to grant access to anyone who has
a pager, plus grant access to Joe Manager, who doesn't
have a pager, but does need to access the same
resource:

An optional second parameter can be added to the
AuthLDAPURL to override
the default connection type set by LDAPTrustedMode.
This will allow the connection established by an ldap:// Url
to be upgraded to a secure connection on the same port.

when this module performs authentication, ldap attributes specified
in the authldapurl
directive are placed in environment variables with the prefix "AUTHENTICATE_".

when this module performs authorization, ldap attributes specified
in the authldapurl
directive are placed in environment variables with the prefix "AUTHORIZE_".

If the attribute field contains the username, common name
and telephone number of a user, a CGI program will have access to
this information without the need to make a second independent LDAP
query to gather this additional information.

This has the potential to dramatically simplify the coding and
configuration required in some web applications.

An Active Directory installation may support multiple domains at the
same time. To distinguish users between domains, an identifier called
a User Principle Name (UPN) can be added to a user's entry in the
directory. This UPN usually takes the form of the user's account
name, followed by the domain components of the particular domain,
for example somebody@nz.example.com.

You may wish to configure the mod_authnz_ldap
module to authenticate users present in any of the domains making up
the Active Directory forest. In this way both
somebody@nz.example.com and someone@au.example.com
can be authenticated using the same query at the same time.

To make this practical, Active Directory supports the concept of
a Global Catalog. This Global Catalog is a read only copy of selected
attributes of all the Active Directory servers within the Active
Directory forest. Querying the Global Catalog allows all the domains
to be queried in a single query, without the query spanning servers
over potentially slow links.

If enabled, the Global Catalog is an independent directory server
that runs on port 3268 (3269 for SSL). To search for a user, do a
subtree search for the attribute userPrincipalName, with
an empty search root, like so:

Normally, FrontPage uses FrontPage-web-specific user/group
files (i.e., the mod_authn_file and
mod_authz_groupfile modules) to handle all
authentication. Unfortunately, it is not possible to just
change to LDAP authentication by adding the proper directives,
because it will break the Permissions forms in
the FrontPage client, which attempt to modify the standard
text-based authorization files.

Once a FrontPage web has been created, adding LDAP
authentication to it is a matter of adding the following
directives to every.htaccess file
that gets created in the web

FrontPage restricts access to a web by adding the Require
valid-user directive to the .htaccess
files. The Require valid-user directive will succeed for
any user who is valid as far as LDAP is
concerned. This means that anybody who has an entry in
the LDAP directory is considered a valid user, whereas FrontPage
considers only those people in the local user file to be
valid. By substituting the ldap-group with group file authorization,
Apache is allowed to consult the local user file (which is managed by
FrontPage) - instead of LDAP - when handling authorizing the user.

Once directives have been added as specified above,
FrontPage users will be able to perform all management
operations from the FrontPage client.

When choosing the LDAP URL, the attribute to use for
authentication should be something that will also be valid
for putting into a mod_authn_file user file.
The user ID is ideal for this.

When adding users via FrontPage, FrontPage administrators
should choose usernames that already exist in the LDAP
directory (for obvious reasons). Also, the password that the
administrator enters into the form is ignored, since Apache
will actually be authenticating against the password in the
LDAP database, and not against the password in the local user
file. This could cause confusion for web administrators.

The directives must be put in the .htaccess
files. Attempting to put them inside <Location> or <Directory> directives won't work. This
is because mod_authnz_ldap has to be able to grab
the AuthGroupFile
directive that is found in FrontPage .htaccess
files so that it knows where to look for the valid user list. If
the mod_authnz_ldap directives aren't in the same
.htaccess file as the FrontPage directives, then
the hack won't work, because mod_authnz_ldap will
never get a chance to process the .htaccess file,
and won't be able to find the FrontPage-managed user file.

This directive allows you to override the prefix used for environment
variables set during LDAP authorization. If AUTHENTICATE_ is
specified, consumers of these environment variables see the same information
whether LDAP has performed authentication, authorization, or both.

Note

No authorization variables are set when a user is authorized on the basis of
Require valid-user.

By default, subsequent authentication providers are only queried if a
user cannot be mapped to a DN, but not if the user can be mapped to a DN and their
password cannot be verified with an LDAP bind.
If AuthLDAPBindAuthoritative
is set to off, other configured authentication modules will have
a chance to validate the user if the LDAP bind (with the current user's credentials)
fails for any reason.

This allows users present in both LDAP and
AuthUserFile to authenticate
when the LDAP server is available but the user's account is locked or password
is otherwise unusable.

A bind password to use in conjunction with the bind DN. Note
that the bind password is probably sensitive data, and should be
properly protected. You should only use the AuthLDAPBindDN and AuthLDAPBindPassword if you
absolutely need them to search the directory.

If the value begins with exec: the resulting command will be
executed and the first line returned to standard output by the
program will be used as the password.

The AuthLDAPCharsetConfig directive sets the location
of the language to charset conversion configuration file. File-path is relative
to the ServerRoot. This file specifies
the list of language extensions to character sets.
Most administrators use the provided charset.conv
file, which associates common language extensions to character sets.

The file contains lines in the following format:

Language-Extensioncharset [Language-String] ...

The case of the extension does not matter. Blank lines, and lines
beginning with a hash character (#) are ignored.

When set, and mod_authnz_ldap has authenticated the
user, LDAP comparisons for authorization use the queried distinguished name (DN)
and HTTP basic authentication password of the authenticated user instead of
the servers configured credentials.

When set, mod_authnz_ldap will use the LDAP
server to compare the DNs. This is the only foolproof way to
compare DNs. mod_authnz_ldap will search the
directory for the DN specified with the Require dn directive, then,
retrieve the DN and compare it with the DN retrieved from the user
entry. If this directive is not set,
mod_authnz_ldap simply does a string comparison. It
is possible to get false negatives with this approach, but it is
much faster. Note the mod_ldap cache can speed up
DN comparison in most situations.

This directive specifies which LDAP attributes are used to
check for user members within groups. Multiple attributes can be used
by specifying this directive multiple times. If not specified,
then mod_authnz_ldap uses the member and
uniquemember attributes.

When set on, this directive says to use the
distinguished name of the client username when checking for group
membership. Otherwise, the username will be used. For example,
assume that the client sent the username bjenson,
which corresponds to the LDAP DN cn=Babs Jenson,
o=Example. If this directive is set,
mod_authnz_ldap will check if the group has
cn=Babs Jenson, o=Example as a member. If this
directive is not set, then mod_authnz_ldap will
check if the group has bjenson as a member.

By default, the server either anonymously, or with a dedicated user and
password, converts the basic authentication username into an LDAP
distinguished name (DN). This directive forces the server to use the verbatim username
and password provided by the incoming user to perform the initial DN
search.

When this directive is set to a non-zero value X
combined with use of the Require ldap-group someGroupDN
directive, the provided user credentials will be searched for
as a member of the someGroupDN directory object or of
any group member of the current group up to the maximum nesting
level X specified by this directive.

Nested groups performance

When AuthLDAPSubGroupAttribute overlaps with
AuthLDAPGroupAttribute (as it does by default and
as required by common LDAP schemas), uncached searching for subgroups in
large groups can be very slow. If you use large, non-nested groups, set
AuthLDAPMaxSubGroupDepth to zero.

If this directive is set, the value of the
REMOTE_USER environment variable will be set to the
value of the attribute specified. Make sure that this attribute is
included in the list of attributes in the AuthLDAPUrl definition,
otherwise this directive will have no effect. This directive, if
present, takes precedence over AuthLDAPRemoteUserIsDN. This
directive is useful should you want people to log into a website
using an email address, but a backend application expects the
username as a userid.

If this directive is set to on, the value of the
REMOTE_USER environment variable will be set to the full
distinguished name of the authenticated user, rather than just
the username that was passed by the client. It is turned off by
default.

When set, and mod_authnz_ldap has authenticated the
user, LDAP searches for authorization use the queried distinguished name (DN)
and HTTP basic authentication password of the authenticated user instead of
the servers configured credentials.

The ldap-filter and ldap-dn authorization
checks use searches.

This directive only has effect on the comparisons performed during
nested group processing when
AuthLDAPCompareAsUser is also enabled.

This directive should only be used when your LDAP server doesn't
accept anonymous searches and you cannot use a dedicated
AuthLDAPBindDN.

An LDAP group object may contain members that are users and
members that are groups (called nested or sub groups). The
AuthLDAPSubGroupAttribute directive identifies the
labels of group members and the AuthLDAPGroupAttribute
directive identifies the labels of the user members. Multiple
attributes can be used by specifying this directive multiple times.
If not specified, then mod_authnz_ldap uses the
member and uniqueMember attributes.

An LDAP group object may contain members that are users and
members that are groups (called nested or sub groups). The
AuthLDAPSubGroupAttribute
directive identifies the
labels of members that may be sub-groups of the current group
(as opposed to user members). The AuthLDAPSubGroupClass
directive specifies the LDAP objectClass values used in verifying that
these potential sub-groups are in fact group objects. Verified sub-groups
can then be searched for more user or sub-group members. Multiple
attributes can be used by specifying this directive multiple times.
If not specified, then mod_authnz_ldap uses the
groupOfNames and groupOfUniqueNames values.

An RFC 2255 URL which specifies the LDAP search parameters
to use. The syntax of the URL is

ldap://host:port/basedn?attribute?scope?filter

If you want to specify more than one LDAP URL that Apache should try in turn, the syntax is:

AuthLDAPUrl "ldap://ldap1.example.com ldap2.example.com/dc=..."

Caveat: If you specify multiple servers, you need to enclose the entire URL string in quotes;
otherwise you will get an error: "AuthLDAPURL takes one argument, URL to define LDAP connection.."
You can of course use search parameters on each of these.

ldap

For regular ldap, use the
string ldap. For secure LDAP, use ldaps
instead. Secure LDAP is only available if Apache was linked
to an LDAP library with SSL support.

host:port

The name/port of the ldap server (defaults to
localhost:389 for ldap, and
localhost:636 for ldaps). To
specify multiple, redundant LDAP servers, just list all
servers, separated by spaces. mod_authnz_ldap
will try connecting to each server in turn, until it makes a
successful connection. If multiple ldap servers are specified,
then entire LDAP URL must be encapsulated in double quotes.

Once a connection has been made to a server, that
connection remains active for the life of the
httpd process, or until the LDAP server goes
down.

If the LDAP server goes down and breaks an existing
connection, mod_authnz_ldap will attempt to
re-connect, starting with the primary server, and trying
each redundant server in turn. Note that this is different
than a true round-robin search.

basedn

The DN of the branch of the
directory where all searches should start from. At the very
least, this must be the top of your directory tree, but
could also specify a subtree in the directory.

attribute

The attribute to search for.
Although RFC 2255 allows a comma-separated list of
attributes, only the first attribute will be used, no
matter how many are provided. If no attributes are
provided, the default is to use uid. It's a good
idea to choose an attribute that will be unique across all
entries in the subtree you will be using. All attributes
listed will be put into the environment with an AUTHENTICATE_ prefix
for use by other modules.

scope

The scope of the search. Can be either one or
sub. Note that a scope of base is
also supported by RFC 2255, but is not supported by this
module. If the scope is not provided, or if base scope
is specified, the default is to use a scope of
sub.

filter

A valid LDAP search filter. If
not provided, defaults to (objectClass=*), which
will search for all objects in the tree. Filters are
limited to approximately 8000 characters (the definition of
MAX_STRING_LEN in the Apache source code). This
should be more than sufficient for any application. In 2.4.10 and later,
the keyword none disables the use of a filter; this is
required by some primitive LDAP servers.

When doing searches, the attribute, filter and username passed
by the HTTP client are combined to create a search filter that
looks like
(&(filter)(attribute=username)).

For example, consider an URL of
ldap://ldap.example.com/o=Example?cn?sub?(posixid=*). When
a client attempts to connect using a username of Babs
Jenson, the resulting search filter will be
(&(posixid=*)(cn=Babs Jenson)).

An optional parameter can be added to allow the LDAP Url to override
the connection type. This parameter can be one of the following:

NONE

Establish an unsecure connection on the default LDAP port. This
is the same as ldap:// on port 389.

SSL

Establish a secure connection on the default secure LDAP port.
This is the same as ldaps://

TLS | STARTTLS

Establish an upgraded secure connection on the default LDAP port.
This connection will be initiated on port 389 by default and then
upgraded to a secure connection on the same port.

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